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Description of upgrade

The CAMS IFS cycle 50R1 is based on ECMWF's IFS Cycle 50r1.

The CAMS datasets affected by the upgrade are:

CAMS global atmospheric composition forecasts (COMPO)
CAMS global greenhouse gas forecasts (GHG)

Timetable for implementation

The planned timetable for the implementation of the cycle 50R1 is as follows:

Date	Event
late April 2025	Implementation

The timetable represents current expectations and may change in light of actual progress made.

Current Status

IFS cycle 50R1 is going through its final preparation phase.

Meteorological content of the new cycle

The meteorological changes can be found on the ECMWF IFS CY50R1 page.

Atmospheric composition and greenhouse gas upgrades of the new cycle

Assimilation

Updated background errors for NWP, now taken from the operational EDA (COMPO)
Updated background errors for O3 to remove spurious long-range correlations (COMPO)
The EDA-based B matrix used in 49r1 is tapered in the stratosphere for 50r1 for CH4 (GHG)
The EDA-based B matrix used in 49r1 is tapered near the surface in 50r1 for CO2 (GHG)

Observations

Sentinel 3 AOD over ocean actively assimilated (COMPO)
TROPOMI for CH4 (GHG)

Emissions

CAMS-GLOB-ANT-M1, a merged emission data set using regional emissions inventories for North-America (EPA), Europe (CAMS-REG) and China (MECS) and Edgar 6.2 elsewhere (COMPO)
Activation of weekly cycle in anthropogenic emissions
Online BVOC emissions simulation (COMPO)
New GFAS emissions 1.4.2 (MODIS and VIIRS-based)

Model changes

Aerosol developments (COMPO):

Implementation of an equilibration time parameterization for nitrate/ammonium formation
Revision of hydrophilic growth of OM, SOA and fine mode nitrate
Correction of hydrophilic growth factor of sea salt for sedimentation
Sedimentation velocity computed online for all species, using the Stokes formula

Reactive gases developments (COMPO):

Update of heterogeneous chemistry parameterization
Revision of SO2 + H2O2 aqueous phase reaction

Impact of the new cycle

Technical details of the new cycle

Please note: 3 hourly analysis fields now available

With the implementation of the IFS Cycle 50r1 analysis fields will be available every 3 hours, at times 0 UTC, 3 UTC ... 18 UTC and 21 UTC.
(Previously, analysis fields were available only every 6 hours, at times 0 UTC, 6 UTC, 12 UTC and 18 UTC.)

Please note: Hourly forecast fields now available

With the implementation of the IFS Cycle 50r1 model level and pressure level forecast fields will be available every hourly step at 0, 1, 2 ... 119 and 120.
(Previously, only surface level forecast fields were available every hourly step).

New parameters

paramId	shortName	name	units	GRIB edition	Components
Model & Pressure levels
216013	MolBSC355	Molecular backscatter coefficient at 355 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216014	MolBSC532	Molecular backscatter coefficient at 532 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216015	MolBSC1064	Molecular backscatter coefficient at 1064 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216023	MolBSC910	Molecular backscatter coefficient at 910 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216016	AerBSC355	Aerosol backscatter coefficient at 355 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216017	AerBSC532	Aerosol backscatter coefficient at 355 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216018	AerBSC1064	Aerosol backscatter coefficient at 355 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216024	AerBSC910	Aerosol backscatter coefficient at 355 nm	m^-1 sr^-1	2	CAMS Aerosol Model
216025	Aerext340	Aerosol extinction coefficient at 340 nm	m^-1	2	CAMS Aerosol Model
216026	Aerext440	Aerosol extinction coefficient at 440 nm	m^-1	2	CAMS Aerosol Model
216027	Aerext800	Aerosol extinction coefficient at 800 nm	m^-1	2	CAMS Aerosol Model
216019	Aerext910	Aerosol extinction coefficient at 910 nm	m^-1	2	CAMS Aerosol Model
216020	SSA910	Single Scattering Albedo at 910 nm		2	CAMS Aerosol Model
216022	Aerbcksctgnd910	Aerosol backscatter coefficient at 910 nm as seen from the ground	m^-1 sr^-1	2	CAMS Aerosol Model
216021	Aerbckscttoa910	Aerosol backscatter coefficient at 910 nm as seen from TOA	m^-1 sr^-1	2	CAMS Aerosol Model
Surface level
216033	trco3	Tropospheric column vertically-integrated mass density of ozone	kg m^-2	2	CAMS Chemical Model
216034	trcco	Tropospheric column vertically-integrated mass density of carbon monoxide	kg m^-2	2	CAMS Chemical Model
216035	trcno2	Tropospheric column vertically-integrated mass density of nitrogen dioxide	kg m^-2	2	CAMS Chemical Model

Change to GRIB encoding

The GRIB model identifiers (generating process identification number) for cycle 50r1 will be changed as follows:

GRIB 1 Section 1 Octets	GRIB 2 Section 4 Octets	ecCodes key	Component	Model identifier
GRIB 1 Section 1 Octets	GRIB 2 Section 4 Octets	ecCodes key	Component	49r1	50r1
6	14	generatingProcessIdentifier	Atmospheric model	158	161
6	14	generatingProcessIdentifier	Ocean wave model	106	109
6	14	generatingProcessIdentifier	soil moisture model	146	146

For all parameters in GRIB 2 the Master Tables Version Number will be changed as follows:

GRIB 2

Section 1

Octets

ecCodes key

Master Tables Version Number

49r1

50r1

10

tablesVersion

33

35

Software

To handle the data of Cycle 50r1 we recommend to use the ECMWF software packages

ecCodes (2.44.0)
CodesUI (minimum version)
Magics (4.16.0)
Metview (5.26.1)
ODC (1.6.0)

On the ATOS HPC these versions correspond to ecmwf-toolbox/2025.1

Availability of test data from the cycle 50r1 test suites

The CAMS operational ECMWF data portal (aux.ecmwf.int; SFTP/FTP/HTTPS data access) will serve the most recent 3 days of test data, once the e-suite is running in near-real-time, in the directories "/DATA/CAMS_GLOBAL_TEST" and "/DATA/CAMS_EUROPE_BC_TEST" for global and regional boundary condition data, respectively.

In addition, surface level fields (model level 137) will be provided as individual files in the "/DATA/CAMS_GLOBAL_ADDITIONAL_TEST" directory.

Users wanting to access the output from the current test system for a longer period can access the data from <> onwards directly on MARS or through the Atmosphere Data Store. More details can be found here: Accessing CAMS 50r1 test data.

_{This document has been produced in the context of the} _{Copernicus Atmosphere Monitoring Service (CAMS)}_.

_{The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of CAMS on behalf of the European Union (Delegation Agreement signed on 11/11/2014 and Contribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.}

_{The users thereof use the information at their sole risk and liability. For the avoidance of all doubt , the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view.}